Genetic Variant NM_022132.5:c.499T>A (chr5-71602621-T-A) – ACMG Classification: Pathogenic (10 pts)

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1PM2PM5PP3_Strong

The NM_022132.5(MCCC2):c.499T>A(p.Cys167Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,864 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C167R) has been classified as Likely pathogenic.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

MCCC2
NM_022132.5 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 7.99

Publications

0 publications found

Variant links:

Genes affected

MCCC2 (HGNC:6937): (methylcrotonyl-CoA carboxylase subunit 2) This gene encodes the small subunit of 3-methylcrotonyl-CoA carboxylase. This enzyme functions as a heterodimer and catalyzes the carboxylation of 3-methylcrotonyl-CoA to form 3-methylglutaconyl-CoA. Mutations in this gene are associated with 3-Methylcrotonylglycinuria, an autosomal recessive disorder of leucine catabolism. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, May 2018]

MCCC2 Gene-Disease associations (from GenCC):

3-methylcrotonyl-CoA carboxylase 2 deficiency
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
3-methylcrotonyl-CoA carboxylase deficiency
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet

MCCC2 links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PM1

In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain in NM_022132.5

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr5-71602621-T-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 1923.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.972

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MCCC2	NM_022132.5 link	c.499T>A	p.Cys167Ser	missense_variant	Exon 5 of 17	ENST00000340941.11	NP_071415.1	Q9HCC0-1A0A140VK29

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MCCC2	ENST00000340941.11 link	c.499T>A	p.Cys167Ser	missense_variant	Exon 5 of 17	1	NM_022132.5	ENSP00000343657.6		Q9HCC0-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461864

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727234

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39688

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.0000187

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1112002

Other (OTH)

AF:

0.00

AC:

AN:

60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.52

BayesDel_addAF

Pathogenic

0.42

BayesDel_noAF

Pathogenic

0.37

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.79

D;D;.

Eigen

Pathogenic

0.88

Eigen_PC

Pathogenic

0.83

FATHMM_MKL

Pathogenic

0.97

LIST_S2

Pathogenic

0.98

D;D;D

M_CAP

Pathogenic

0.46

MetaRNN

Pathogenic

0.97

D;D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.3

.;M;.

PhyloP100

8.0

PrimateAI

Uncertain

0.59

PROVEAN

Pathogenic

-9.6

.;D;D

REVEL

Pathogenic

0.90

Sift

Pathogenic

0.0

.;D;D

Sift4G

Uncertain

0.022

D;D;D

Polyphen

1.0

.;D;D

Vest4

0.85

MutPred

0.79

Loss of catalytic residue at P166 (P = 0.0148);Loss of catalytic residue at P166 (P = 0.0148);Loss of catalytic residue at P166 (P = 0.0148);

MVP

0.93

MPC

0.58

ClinPred

1.0

GERP RS

5.5

Varity_R

0.95

gMVP

0.94

Mutation Taster

=6/94

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over